The invention relates to a bone nail for the heel. The invention particularly relates to a bone nail configured to perform an arthrodesis of bones or bone fragments of the hindfoot.
Document US 2006/0200141 A1 describes a bone nail having a straight uncurved and unbent shape that, when being inserted into the hindfoot, extends through the calcaneus, talus and tibia. In order to implant the nail, a straight bore is formed which extends almost vertically through the bones, wherein entry of the bore into the calcaneus is located on the plantar side of the bone. Due to this construction, nerves concentrated on the plantar side of the foot may be damaged such that the patient may suffer from pain due to the implant.
Document US 2006/0241605 A1 shows an intramedullary nail for the tibia with an overall length between 200 and 500 mm and a curved section having a radius of curvature in the range of 300 to 1.300 mm. Only a portion of the nail is curved, which portion basically follows the shape of the tibia marrow canal.
Document WO 2011/072249 A1 discloses an anchor fusion device that substantially combines a hindfoot nail with a tibia marrow nail. The nail may have a length of 300 mm and a portion extending through the tibia has a radius of curvature of about 1.5 m. At a transition region between the tibia and the talus, a sharp bending occurs in 3-dimensional space at an angle of about 10°-15° towards a longitudinal axis of a straight bore extending through the talus and calcaneus, which bore likewise opens towards the plantar side of the calcaneus. Therefore, this construction suffers from the same disadvantages as noted above.
Document WO 2009/067831 A1 proposes an arc-shaped bone nail for the hindfoot, which extends from an axial face of the calcaneus in an almost circular shape through the talus up into the tibia. The bone nail is curved and has a curvature radius of at least 130 mm. Transverse bores are provided along the length of the nail, and at a rear end an inclined bore extends from the rear end at an angle of 15° with respect to a central axis of the nail to an outer surface to allow locking the bone nail via a bone anchor in the calcaneus and talus against forces tending to loosen the nail. The corresponding locking screw has a shank and a head, the shank being formed with a bone thread from the tip of the screw up to the head. The bone nail may have a rounded tip with slits formed therein and a cross-sectional shape of the nail may vary along a front portion, whereas a cross-sectional diameter is substantially constant up to the rear end of the nail.